Semiconductor device manufacturing: process – Coating with electrically or thermally conductive material – To form ohmic contact to semiconductive material
Patent
1996-07-10
1998-11-03
Bowers, Jr., Charles L.
Semiconductor device manufacturing: process
Coating with electrically or thermally conductive material
To form ohmic contact to semiconductive material
438667, 438654, 438687, H01L 2144
Patent
active
058308032
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to a method for filling contact holes in the top side of a semiconductor component.
German Patent Application P 43 04 119 describes a component which is composed of a stack of circuit planes which are arranged one above the other and are connected to contacts. The vertical contacts between the circuit planes are realized by pouring a liquid metal, for example gallium, into prefabricated holes which are lined with a solid metal layer. The two metals alloy together and form a permanent connection, which forms the electrical and mechanical contact. Shortly before the application of the liquid metal, the surface of such a circuit plane provided with contact holes is predominantly composed of a polyimide layer, which cannot be wetted by the metal and in which the contact holes, which have a size of a few micrometers, are situated. The walls of the contact holes are provided with a metal layer (for example nickel or copper when using gallium for the liquid metal) which can be wetted by the liquid metal. The liquid metal is intended to be introduced into the contact holes in such a way that the latter are then completely filled and the surface of the polyimide layer remains dry. Small menisci of the liquid metal are intended to be formed in each case above the contact holes, which menisci project above the surface to a level which is sufficient for the intended application. The formation of the menisci must take place in a highly constant manner over the entire surface, it being intended, in addition, to achieve good reproducibility from wafer to wafer. In addition, it is necessary reliably to prevent residues of the liquid metal from adhering to the polyimide surface and possibly leading to a short circuit when the circuit planes are joined together. It is possible, for example, as described in the patent application specified, to pour the liquid metal on and subsequently peel off the drops which have formed on the surface over the non-wettable polyimide surfaces by means of a rotary movement of the wafer. In this case, the situation may arise where, even after the excess liquid metal has been hurled off, the contact holes, which are very small and are arranged very close together, remain electrically conductively connected, at least in individual cases, on the surface due to webs of the liquid metal. Drops of the liquid metal can adhere to those points at which the polyimide layer is not perfect, for example steps or cracks, and can lead to short circuits if they are pressed into the thin gap between the planes when the circuit planes are joined together.
SUMMARY OF THE INVENTION
The object of the present invention is to specify a method for filling contact holes in the top side of semiconductor components with a liquid metal in which the abovementioned difficulties do not occur.
In general terms the present invention is a method for producing liquid contacts in contact holes on a top side of a semiconductor component. The top side is not wettable by the material provided for the liquid contacts. The walls and edges of the contact holes are wettable by this material. The contact holes are filled such that the material provided for the liquid contacts is applied to the top side by means of a doctor blade. There is situated on a longitudinal edge of the doctor blade an adhesion strip which is made of material which is wetted by the material provided for the liquid contacts. The doctor blade is moved here by the longitudianal edge at a distance over the top side. The material provided for the liquid contacts is moved in the form of a cylinder between the adhesion strip and the surface of the component.
Advantageous developments of the present invention are as follows.
A doctor blade is utilized whose adhesion strip has, on both side surfaces of the doctor blade, strips adjoining the longitudinal edge which is moved over the top side of the component.
Prior to the application of the material provided for the liquid contacts, the top side of the component
REFERENCES:
patent: 5468681 (1995-11-01), Pasch
patent: 5547530 (1996-08-01), Nakamura et al.
patent: 5587342 (1996-12-01), Lin et al.
Patent Abstracts of Japan (E-1235), Jul. 16, 1992, No. 326, Manufacture of Semiconductor Device, Matsuchita Electric Ind Co Ltd., M. Nakatani, JP 4-97530 (30 Mar. 1992).
Patent Abstracts of Japan (E-867), Dec. 27, 1989, No. 594, Method of Filling Through-Hole With Conductor Paste, Hitachi Ltd. K. Takashi et al., JP 12-48592 (04 Oct. 1989).
Bowers Jr. Charles L.
Gurley Lynne A.
Siemens Aktiengesellschaft
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